This article presents the design and experimental evaluation of a low-cost data transmission system based on LoRa technology (433 MHz) for applications in precision agriculture. The aim of the study was to design, implement, and test a low-cost, energy-efficient system capable of wirelessly transmitting information from sensors deployed in agricultural fields—such as soil moisture, temperature, and sunlight data. The tests were conducted with three transmission rates (0.1, 1.0, and 10 kbps) and varying bandwidths and spreading factors. The results showed that transmission at 0.1 kbps with bandwidths of 7.8 kHz and 20.8 kHz achieved less than 1% packet loss up to 150 m. However, this configuration required up to 140 times higher energy consumption compared with high-rate settings (10 kbps). At 10 kbps, almost all packets failed to reach the receiver at distances exceeding 100 m. Variations in reception between test paths were observed and were attributed to terrain and structural conditions (e.g., building reflections), which affected both RSSI and SNR values. The results demonstrate that LoRa technology operating at 433 MHz can provide a reliable foundation for autonomous, distributed monitoring systems in agriculture. This study provides novel quantitative evidence of how specific transmission parameters influence the trade-off between communication reliability and energy efficiency under real field conditions. The findings offer practical guidelines for designing optimized LoRa-based telemetry systems, supporting more informed decision-making in irrigation, fertilization, and crop protection.